1. Field:
This disclosure is concerned generally with blood filtering systems and specifically with a system for the removal of white blood cells from red blood cells.
2. Prior Art:
The desirability of removing white blood cells (WBC) from a mixture of WBCs and red blood cells (RBC) is well known, especially for patients who receive frequent blood transfusions. See, for example abstracts by K. Kleesiek et al (P-9-01) and M. Jochum et al (p-9-02) from Abstracts of the 18th Congress of the International Society of Blood Transfusion, Munich, July 22-27, 1984. See also the article by H. Harke et al, Anaesthesist (1982) 31:165 -171.
In the past, WBCs and platelets associated with febrile reactions have been removed via the reconstitution of frozen blood (which is costly) or by multiple washings with saline of the RBC/WBC mixture (which is time consuming, is less predictable, and results in RBC loss).
Kikugawa et al in Vox Sang., Vol. 34, 281-290 (1975) describe commercial cotton wool filters for filtering blood to remove the above HLA antigen. These filters are, however, expensive and cumbersome to use.
Diepenhorst et al in Vox Sang., Vol. 23, 308-320 (1972) and Vol. 29, 15-22 (1975) disclose cotton wool filtration of blood under pressure. This method, while efficient, requires a special apparatus that is expensive.
All of the above techniques require that the treated blood be infused wihtin 24 hours of treatment in order to avoid the potential risk of infection. Prolonged shelf life of blood so treated is not possible.
Some of the above shortcomings have been addressed in patent application Ser. No. 06/385,167 filed in the name of L. Wisdom on June 4, 1982, entitled "Blood Bag System with Integral Filtering Means", the teachings of which are incorporated herein by reference thereto. The present disclosure represents an improvement over the system and methods disclosed in that application and details of the improved system and method of filtration are described below.